Solar power plants produce electric power on a large scale by collecting incident light and converting the collected light into electricity by means of a large number of PV-modules. Conventional PV-modules for electricity production may be based on many different kinds of PV-cells such as c-Si (e.g. mono-crystalline, multi-crystalline, quasimono-crystalline or “string-ribbon”), a-Si (amorphous silicon), a-Si/NC-Si (amorphous silicon/nano-crystalline silicon), a-Si/SiGe (amorphous silicon/silicon-germanium), CdTe (cadmium telluride), GIGS (copper indium gallium selenide), CIS (copper indium sulphide), but a common feature of conventional PV-modules is that they are limited in their electrical power (typically to less than 300 W) by limitations on their physical size. Typical PV-modules used in large scale installations are planar and have a frontal- and sometimes also rear face which is made from planar glass. The frontal glass is often of special low-iron (Fe) content and is typically hardened. The glass-content in these panels, which is on the order of 15-20 kg in a PV-module with a nameplate power of 200-300 W, makes them very heavy and expensive. Furthermore, such conventional glass-plate PV-modules are rigid which places a practical upper limit on their size—and therefore also places upper limits to their electrical power. PV electricity production in large installations of several megawatts (MW) typically uses such rigid modules which must be mounted manually onto metallic racking hardware in order to avoid wind-induced damage and such that the modules are fixed in a beneficial angle with respect to the sun. After mounting, the PV-modules must be connected electrically from one PV-module to the next PV-module using external connectors, which is typically also a manual process. A conventional PV power plant with a name plate power of 250 MW will therefore contain on the order of 1 million such PV-modules and an equally large number of connectors which is a source of reliability- and maintenance problems.
For these reasons, the traditional way to construct a PV power plant carries very high costs, due to high consumption of materials, such as glass in the PV-modules and steel in the racking hardware, cost of transportation to the deployment site, and the large amount of manual labour involved with the installation of the large number of small modules. As a consequence, a PV power plant carries a large capital cost in its construction. To summarize, there are two fundamental problems with traditional PV-modules. The first problem is that that they and their mounting hardware are heavy and contain large amounts of materials like glass, steel, aluminium and other structural materials compared to their electrical power. The second problem is that the individual PV-modules are limited to a very low electrical power compared to typical generators on the electrical high-voltage power grid. As a consequence, it is impractical to erect and maintain PV power plants of just a few hundred MW as they contain more than 1 million individual PV-modules. Furthermore, since conventional glass-plate PV-modules cannot be scaled up because of transportation- and handling problems these rigid PV-modules are poorly suited for large-scale PV power plants. Therefore, there is a need for a new, scalable and resource-efficient technology for making PV power plants.
The prior art discloses collapsible PV-modules, which are fully or partially flexible and may be collapsed by folding or rolling. For example, U.S. Pat. No. 4,713,492 discloses a flat, carpet-like PV-module comprised of a number of discrete, but flexible sub-modules which are hinged together. However, even though referred to as a “large area module” the PV-module disclosed in U.S. Pat. No. 4,713,492 is intended as a mobile power supply that can be stowed away after temporary use. This design is not suited for use in a large-scale solar power plant producing electricity to a power-grid.
A flexible PV-module comprising solar energy converters enclosed within an inflatable envelope is disclosed in US 2001/0054252 A1. The disclosed PV-module is configured for transmitting diffused light, while collecting directional light on the solar energy converter. The design of US 2001/0054252 A1 thus has a very sparse distribution of the actual active solar energy converters results in an ineffective utilisation of footprint which is incompatible with use in a large-scale solar power plant. Furthermore, the PV-module of US 2001/0054252 A1 is intended for integration in a building, and requires at least an additional frame structure as a support.
Another inflatable PV-module is disclosed in DE 198 57 174 A1. The disclosed PV-module is intended for floating deployment on a water surface and therefore inevitably requires a light weight structure with sufficient buoyancy to keep the PV-module afloat.